/****************************************************************************
 * Copyright (C) 2009-2015 EPAM Systems
 *
 * This file is part of Indigo toolkit.
 *
 * This file may be distributed and/or modified under the terms of the
 * GNU General Public License version 3 as published by the Free Software
 * Foundation and appearing in the file LICENSE.GPL included in the
 * packaging of this file.
 *
 * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 ***************************************************************************/

#include "gzip/gzip_scanner.h"

using namespace indigo;

IMPL_ERROR(GZipScanner, "GZip scanner");

CP_DEF(GZipScanner);

GZipScanner::GZipScanner (Scanner &source) :
_source(source),
CP_INIT,
TL_CP_GET(_inbuf),
TL_CP_GET(_outbuf)
{
   _zstream.zalloc = Z_NULL;
   _zstream.zfree = Z_NULL;
   _zstream.opaque = Z_NULL;
   _zstream.avail_in = 0;
   _zstream.next_in = Z_NULL;

   int rc = inflateInit2(&_zstream, 16 + MAX_WBITS);

   if (rc == Z_VERSION_ERROR)
      throw Error("zlib version incompatible");
   if (rc == Z_MEM_ERROR)
      throw Error("not enough memory for zlib");
   if (rc != Z_OK)
      throw Error("unknown zlib error code: %d", rc);

   _outbuf.clear_resize(CHUNK_SIZE);
   _inbuf.clear_resize(CHUNK_SIZE);
   _outbuf_start = 0;
   _inbuf_end = 0;
   _uncompressed_total = 0;
   _eof = false;

   _zstream.avail_out = _outbuf.size();
   _zstream.next_out = _outbuf.ptr();
}

GZipScanner::~GZipScanner ()
{
   inflateEnd(&_zstream);
}

void GZipScanner::read (int length, void *res)
{
   if (res == 0)
      throw Error("zero pointer given");

   if (_outbuf_start < _outbuf.size() - (int)_zstream.avail_out)
   {
      int n = __min(length, CHUNK_SIZE - (int)_zstream.avail_out - _outbuf_start);

      memcpy(res, _outbuf.ptr() + _outbuf_start, n);
      _outbuf_start += n;
      _uncompressed_total += n;
      length -= n;
      res = (char *)res + n;
   }

   if (!_read(length, res))
      throw Error("end of compressed data");
}

bool GZipScanner::_read (int length, void *res)
{
   while (length > 0)
   {
      if (_eof)
         return false;

      if (_zstream.avail_in == 0)
      {
         _inbuf_end = 0;

         if (_source.isEOF())
            throw Error("end of file in source stream");

         do
         {
            _inbuf[_inbuf_end++] = _source.readChar();
         } while (!_source.isEOF() && _inbuf_end < _inbuf.size());
         _zstream.avail_in = _inbuf_end;
         _zstream.next_in = _inbuf.ptr();
      }

      _zstream.avail_out = _outbuf.size();
      _zstream.next_out = _outbuf.ptr();
      _outbuf_start = 0;

      int rc = inflate(&_zstream, Z_NO_FLUSH);

      if (rc == Z_STREAM_ERROR)
         throw Error("inconsistent stream structure");

      if (rc == Z_NEED_DICT)
      {
         inflateEnd(&_zstream);
         throw Error("need a dictionary");
      }

      if (rc == Z_MEM_ERROR)
      {
         inflateEnd(&_zstream);
         throw Error("not enough memory");
      }

      if (rc == Z_DATA_ERROR)
      {
         inflateEnd(&_zstream);
         throw Error("corrupted input data");
      }

      if (rc == Z_BUF_ERROR)
         throw Error("Z_BUF_ERROR (workaround not implemented)");

      if (rc != Z_OK && rc != Z_STREAM_END)
         throw Error("unknown zlib error code: %d", rc);

      int n = __min(length, CHUNK_SIZE - (int)_zstream.avail_out - _outbuf_start);

      if (n > 0 && res != 0)
      {
         memcpy(res, _outbuf.ptr(), n);
         _outbuf_start += n;
         _uncompressed_total += n;
         res = (char *)res + n;
      }

      length -= n;
      
      if (rc == Z_STREAM_END)
         _eof = true;
   }
   
   return true;
}

void GZipScanner::readAll (Array<char> &arr)
{
   arr.clear();

   while (!isEOF())
      arr.push(readByte());
}


void GZipScanner::skip (int length)
{
   QS_DEF(Array<char>, dummy);

   dummy.clear_resize(length);
   read(length, dummy.ptr());
}

int GZipScanner::tell ()
{
   return _uncompressed_total;
}

bool GZipScanner::isEOF ()
{
   if ((unsigned)_outbuf_start + _zstream.avail_out == (unsigned)_outbuf.size())
   {
      if (_eof)
         return true;
      _read(1, 0);
   }
   return _eof && (unsigned)_outbuf_start + _zstream.avail_out == (unsigned)_outbuf.size();
}

void GZipScanner::seek (int pos, int from)
{
   throw Error("not implemented");
}

int GZipScanner::lookNext ()
{
   if (_outbuf_start < _outbuf.size() - (int)_zstream.avail_out)
      return _outbuf[_outbuf_start];

   if (_eof)
      return -1;

   _read(1, 0);

   if (_eof)
      return -1;

   if (_outbuf_start < _outbuf.size() - (int)_zstream.avail_out)
      return _outbuf[_outbuf_start];

   throw Error("internal");
}

int GZipScanner::length ()
{
   throw Error("not implemented");
}